Any way you slice it, Verizon's network solidly beats its competitors nationwide, according to RootMetrics independent network testing. But AT&T is not far behind. And T-Mobile is edging forward, displacing Sprint as a distant third.

T-Mobile also jumped in RootMetrics' rankings, beating Sprint for third place nationwide in terms of overall quality.

"Verizon has recaptured the top spot in speed, while AT&T has slipped a little," Bill Moore, CEO for RootMetrics, said in an interview. "Overall the companies are neck and neck. When it comes to reliability, AT&T is getting closer to parity with Verizon."

RootMetrics released the results from its 2014 Midyear US National RootScore Report on Monday. The report provides insights and comparisons of network performance for the entire United States, within each of the 50 states, as well as in the 125 largest metro areas in the country. RootMetrics testers drove more than 234,000 miles, visited more than 6,4000 indoor locations and conducted more than 5.6 million tests across all 50 states, the company said. The tests RootMetrics conducts measure speed, reliability, call, and text messaging quality among other metrics. It ranks the carriers nationally, but also offers insights into performance based on individual states and local communities.

Verizon took the top spot overall in RootMetrics review of mobile networks for the first half of 2014, but AT&T was a close second.Photo by RootMetrics

According to this most recent report, Verizon led the pack in nearly all aspects of testing, sweeping overall performance, network reliability and network speed across the nation. Verizon was also the top-performing network in data and call categories. The carrier's network performed well at the state level as well as in urban areas.

AT&T, which in a previous test beat Verizon overall for speed, ranked a close second in the latest testing both in terms of speed and reliability and it took the top spot for text messaging.

But Moore said the biggest change in rankings came from T-Mobile, which finished a distant third to Verizon and AT&T, in overall rankings. The company, which has been aggressively building its 4G LTE network, saw great improvement compared to the previous report conducted in the second half of 2013. As a result, it overtook Sprint for the third best overall performing carrier in the US. T-Mobile performed especially well in urban areas, where it's service is concentrated. In fact, it topped or tied for speed in 32 of 125 metro markets.

Even though Sprint fell in RootMetrics' rankings, Moore said it also saw improvement. Moore admitted that Sprint is still finding its way through a difficult network upgrade. For more than a year, the company has been ripping out old infrastructure and replacing it with new gear that will make it easier to leverage the three different frequencies of spectrum it's using to build its 4G LTE network.

"Sprint is in transition," Moore said. "They have not yet been able to take full advantage of the new Spark network."

T-Mobile made great strides in improvement in the first half of 2014, especially in urban areas where it's been deploying its 4G LTE service.Photo by RootMetrics

But Moore said where the company has fully transitioned to the new network, the company has seen big improvements in speed and reliability. The big question is whether those improvements will be enough to catch up to or even surpass Sprint's rivals, he said.

Still, he noted that the improvements RootMetrics' testing saw in each carrier and the dynamic nature of the rankings shows that things are changing quickly in the US wireless market. This is to be expected, he noted, as each of the major carriers has been upgrading their networks and adding capacity with more wireless spectrum. And he said that the upgrades are happening much faster than anticipated. For instance, Verizon's quick roll out of AWS spectrum and T-Mobile's rapid deployment of its 4G network has fuelled those carriers' improvements.

But he said he expects improvements in AT&T's network and Sprint's network will also produce improved results the next time the networks are tested and may even result in AT&T and Sprint each moving up a notch.

"These results show that the industry is constantly changing," Moore said. "Every network goes through a build out phase, where performance is high. Then they get some load on the network and it's not as fast."

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